LeslieRushforth

Mercedes make the speedometer to read 2 M.P.H faster than the car is actualy traveling.
This I presume is to drive with in the speed limits as there are now many lasar and radar traps

I have a GPS speed camera detector which in it,s data base stores the location of the cameras then warns the driver 300 yards before you reach the camera.

The data base can be upgraded as to where new cameras are sighted by downloading the information on the computer.

It also as a digital speed reading on the detector which calculates the speed by GPS.

This allways shows a differance of 2 M.P.H at any speed.

Also I have a lasar defuser ......which hit by a police lasar gun will return a NONE reading on the gun.

The defuser is hooked up to the detector which warns the driver.

THIS IS ILLEGAL TO INSTALL THE DEFUSER ON IT,S OWN.

BUT....BUT.....QUOTE > I have a lasar garage door opener which detects the approach of the car by laser then the defuser fires the laser back which activates the door opener, the laser signal is coded for security reasons so that it only recogonise the signal from the car.

THIS IS LEGAL TO INSTALL AT THE MOMENT......FOR HOW LONG ?.

The system don,t come cheap around £700....$1250 U.S.

Have Fun

Les.....Chesterfield U.K.

KirkP

I don't have any speed-measuring deflector equipment, but I think that "only" a 2-MPH speedometer discrepancy is pretty exceptional for any production car.

That said, when I first got my C55, I tested the speedometer accuracy vs. my Garmin V GPS, and comparing the digital speedometer readout of the C55 vs. the GPS at any steady speed between 60 to 90 MPH, the C55 read *exactly* the same speed as the GPS (so I don't have any *honest* excuse regarding "speedometer inaccuracy" to say to a cop if I get pulled over). I'm sure my results may vary by country, higher speeds, & MB model, but that's what I've noted FWIW.

--kirk

blaze1539

A good way to find out if your speedometer is accurate is to have it checked by AAA. If you are a member they can check it for free, contact your local office and they can give you all the info.

JimPurdy

I too have checked my speedometer with my GPS. The speedometer seems to be within 1 mph from the GPS speed.

rbordel

I have checked my Mercedes' speedometer against a GPS receiver, too. I saw no error (well, <1mph, which is the resolution of the GPS receiver.) The speedometer on my Honda Accord is about 2 mph optimistic.

pa28pilot

I seem to recall in the U.S. Federal Motor Vehicle standards a regulation to the effect that speedometers should read around 5 MPH high. I was offended, but not entirely surprised to see it there. It was a long time ago, so I can't cite the section. Does anyone else remember seeing this?

jim256

Could not be....if the govt made them do it there'd be another big yellow and black sticker with permanent glue on it on the speedo!

CASL55

I have read (I think it was either in the PCA house magazine or Roundel) that there is a German law that requires that the speedometer not read lower than the actual speed given any combination of

1) Tire inflation
2) Tire selection (on original rims)
3) Wheel selection (that accept the original tires)
4) Speedometer measurement error
5) Temperature (over the operaing range of the vehicle)

Engineers setting up a speedometer to obey this law would have to put the nominal setting of the speedomter higher than accurate to compensate for the effect of all these errors.

On my wife's 2001 540i, the trip computer calculates average speed independent of the speedometer. On that car, I can set the cruise control so that the speedometer reads 80, reset the speed calculator on the trip computer, and it will read 77 mph.

I realize that what I'm saying is essentially a rumor since I can't give you my source. Does anyone have real information?

Jim